"Is it not by the light which comes from them that we have gained all
our knowledge of the constitution of the heavenly bodies?" I continued.
"A ray from the remotest star brings in its heart a secret message to
him who can read it. Now, the Martians would naturally resort to the
same medium of communication as the most obvious, simple, and
practicable. By producing a powerful light they might hope to attract
our attention, and by imbuing it with characteristic spectra, easily
recognised and changed at intervals, they would distinguish the light
from every other, and show us that it must have had an intelligent
origin."

"What then?"

"We should know that the Martians had a civilisation at least as high as
our own. To my mind, that would be a great discovery--the greatest since
the world began."

"But of little use to either party."

"As for that, a good many of our discoveries, especially in astronomy,
are not of muc